EP3453850B1 - Variable valve drive - Google Patents

Description

The invention relates to a variable valve drive for an internal combustion engine.

It is generally known to use variable valve drives for changing switching times and valve lifts of gas exchange valves of an internal combustion engine during operation of the internal combustion engine. A large number of variable valve trains are known in the prior art.

The US 2005/0150472 A1 discloses an example of a variable valve train. The variable valve train has a camshaft which is rotatably mounted on a fixed part of the engine and comprises a cam. A first rocker arm is pivotably mounted on a fixed part of the engine. The first rocker arm is engaged with a stem of an engine valve. A rotatable drum is carried by a fixed part of the motor and at least partially surrounds the cam. A second rocker arm is pivotably mounted on the drum. A control element is provided for rotating the drum. The second rocker arm has a cam follower that follows the cam of the camshaft. The first rocker arm has a roller in contact with a support surface of the second rocker arm.

The JP H06 10633 A discloses a system with a rocker arm operating a valve. Another lever transfers a cam contour of a cam to the rocker arm. The further lever is pivotably mounted on a pin which is held by a pin holder. The pen holder is fixedly attached to a rotatable gear that can be rotated by a drive gear to adjust the valve control cam.

The DE 42 20 816 A1 discloses several designs for variable valve trains. In one embodiment, a rocker arm is provided in which a cam follower is slidably mounted. The cam carrier is shifted by means of a lever construction and a rotatable shaft.

Other variable valve trains with rocker arms are, for example, from the US 2009/0151674 A1 and the DE 10 2004 040 652 A1 known.

A disadvantage of known variable valve trains, such as the variable valve train from the US 2005/0150472 A1 , is that these often have a complicated structure, a large number of parts and / or a large installation space.

The invention is therefore based on the object of creating an improved variable valve drive with which the disadvantages in the prior art can be overcome. In particular, the variable valve drive should have a simple structure, few parts and / or only a small amount of installation space.

The object is achieved by a variable valve train according to the independent claim. Advantageous developments are given in the dependent claims and the description.

The variable valve train is suitable for an internal combustion engine. The variable valve train has a camshaft with a cam. The variable valve drive has a rocker arm for actuating at least one gas exchange valve of the internal combustion engine. The variable valve train has a pivot lever element, in particular a pivot lever link, which has a contact surface and a cam follower. The contact surface is in operative connection, in particular in contact, with the rocker arm and the cam follower follows a cam contour of the cam. The variable valve drive has a first lever arm which pivots the pivot lever element and which is connected to a drivable pivot shaft for pivoting about a longitudinal axis of the pivot shaft.

The variable valve drive enables a variable transmission of the cam contour to the rocker arm by changing a position of a pivot axis which pivotally connects the pivot lever element to the first lever arm. In detail, an adjustment of the lever arm by means of the pivot shaft causes the position of the pivot axis to be changed, which leads to a displacement movement of the pivot lever element. The contact positions between the rocker arm, the pivot lever element and the cam change. The changed contact positions can be used to implement different "translations" of the cam contour on the rocker arm through the swivel lever element and thus to influence the height of the maximum valve lift.

In order to ensure the variability of the valve train, only a few additional parts are required compared to a non-variable valve train. These include in particular the first lever arm and the pivot lever element. The comparatively simple construction also enables a robust system and, depending on the design, requires little additional space.

The rocker arm can preferably be in operative connection with the cam for actuating the at least one gas exchange valve via the contact surface of the swivel lever element and the cam follower of the swivel lever element.

In one embodiment, the rocker arm is mounted pivotably about the pivot shaft. Additionally or alternatively, the pivot shaft serves as a rocker arm axis for the rocker arm. Such a configuration considerably reduces the installation space of the variable valve drive, since it is not necessary to provide a shaft for pivoting the first lever arm and a rocker arm axis for the pivotable connection to the rocker arm separately from one another.

In a further exemplary embodiment, a rotation of the pivot shaft causes the first lever arm and the pivot lever element to pivot, so that a transmission the cam contour of the cam is variable from the pivot lever element to the rocker arm, in particular steplessly. The valve lift curve transmitted to the at least one gas exchange valve can be changed by changing the position of the pivot axis which pivotally connects the first lever arm and the pivot lever element by pivoting the first lever arm.

In one development, the transmission can be changed to change a valve lift maximum of the at least one gas exchange valve, in particular up to a zero lift of the at least one gas exchange valve. This has the advantage that the amount of gas flowing through the gas exchange valve can be varied by the variable valve drive, in particular up to blocking the gas amount by keeping the gas exchange valve closed, which can be used, for example, for cylinder deactivation.

In one embodiment, the first lever arm is connected to the pivot shaft in a rotationally fixed manner. Due to the rigid connection, a rotary movement of the pivot shaft can be transmitted directly to the first lever arm for pivoting the same. The first lever arm can be directly non-rotatably connected to the pivot shaft or indirectly non-rotatably connected to the pivot shaft via an interposition of one or more intermediate members, for example a sleeve surrounding the pivot shaft.

It is also possible to use a different connection between the first lever arm and the pivot shaft which causes the first lever arm to pivot when the pivot shaft rotates.

In a further embodiment variant, the pivot lever element is pivoted relative to the first lever arm when the cam follower follows the cam contour of the cam. Alternatively or additionally, a pivot axis is provided which connects the first lever arm and the pivot lever element to one another in a pivotable manner. The pivotable connection (pivot axis) between the pivot lever element and the first lever arm can thus fulfill two tasks. On the one hand, the pivoting lever element can be pivoted in order to follow the cam contour of the cam. On the other hand, the connection (pivot axis) serves as a suspension for the pivot lever element, the position of which can be changed by means of the first lever arm in order to change the valve lift curve of the at least one gas exchange valve.

In one embodiment, the rocker arm has a rotatable roller for contacting the contact surface. The rotatable roller can rest on the contact surface. The contact surface can have a continuous profile. The rotatable roller can enable a stepless adjustment of the variable valve train.

In a further development, the cam follower of the swivel lever element and the rotatable roller of the rocker arm can be designed identically. This means that the cam follower and the role of the rocker arm can be designed as identical parts. This reduces the variety of parts.

In a further embodiment, the contact surface is concave. The contact surface can, however, also be implemented flat or convex. This depends on the selected lever ratios of the valve train.

In an embodiment variant, the pivot shaft can only be rotated in a limited angular range of less than 360 °, in particular in an angular range of less than 120 °. This can be due to the fact that the first lever arm only has to be pivoted in a small angular range in order to pivot the pivot lever element in order to change the transmission of the cam contour to the rocker arm. The limited angular range required for rotating the pivot shaft can have an influence on a drive unit of the pivot shaft and a connection between the drive unit and the pivot shaft.

The pivot shaft can preferably be rotatably mounted in bearing blocks which are preferably fastened to a cylinder head of the internal combustion engine.

In a further embodiment variant, the variable valve drive has a second lever arm which is connected to the first lever arm via the pivot shaft and, in particular, via the pivot axis. The first lever arm and the second lever arm can in particular be arranged on opposite sides of the rocker arm. A particularly secure mounting for the swivel lever element can be made possible via two lever arms. The arrangement on opposite sides of the rocker arm can be advantageous for reasons of space.

The first lever arm can preferably be designed like the second lever arm. The first lever arm and the second lever arm can thus be designed as identical parts. This reduces the variety of parts.

In one embodiment, the variable valve drive also has a sleeve which is arranged on the pivot shaft in a rotationally fixed manner. The first lever arm and / or the second lever arm is non-rotatably arranged on the sleeve. The rocker arm is pivotably arranged around the sleeve. This can considerably simplify assembly of the variable valve drive, since an assembly consisting of sleeve, lever arm (s) and rocker arm can be preassembled and then connected to the pivot shaft in a rotationally fixed manner. In particular in the case of embodiments with a plurality of variable valve trains for a plurality of cylinders of the internal combustion engine, this can improve the mountability.

In a further embodiment, the pivot lever element is arranged between the rocker arm and the camshaft. This is advantageous for reasons of space.

In a further exemplary embodiment, the variable valve drive has a drive unit for rotating the pivot shaft. The drive unit is drivingly connected to the pivot shaft. The drive unit can be connected to the pivot shaft and / or the drive unit can be designed such that rotation of the pivot shaft is only possible within a limited angular range. For example, a corresponding electric servomotor with an angular range can be used.

Alternatively, the variable valve drive can have, for example, an actuator which is designed to contact the first lever arm for pivoting the first lever arm. The lever arm can, for example, be adjusted in several stages (in particular in two stages) via the actuator. When using the actuator to adjust the first lever arm, at least one actuator must be provided for each cylinder. Furthermore, stops can be provided to limit the adjustment of the first lever arm.

In a further embodiment variant, the variable valve drive has a camshaft adjuster, which is connected to the camshaft for adjusting a phase of the camshaft. This allows the variability of the variable valve drive to be increased, since in particular the valve lift curves can be shifted, ie. H. the opening and closing times of the gas exchange valves or the gas exchange valve can be changed.

The invention can be used particularly advantageously in a motor vehicle, in particular a commercial vehicle (for example an omnibus or truck). The motor vehicle has the variable valve train as disclosed herein.

However, it is also possible to use the variable valve train in internal combustion engines that are not included in motor vehicles. For example, it can be stationary internal combustion engines, internal combustion engines on ships or in locomotives.

Figur 1

eine Schnittdarstellung eines beispielhaften variablen Ventiltriebs in einem Zustand, in dem ein Nockenfolger des variablen Ventiltriebs in Kontakt mit einem Grundkreisbereich eines Nockens der Nockenwelle ist;

Figur 2

eine weitere Schnittdarstellung des beispielhaften variablen Ventiltriebs in einem Zustand, in dem der Nockenfolger des variablen Ventiltriebs in Kontakt mit einem Ventilhubbereich des Nockens der Nockenwelle ist;

Figur 3

eine perspektivische Ansicht des beispielhaften variablen Ventiltriebs;

Figur 4

eine weitere Schnittdarstellung des beispielhaften variablen Ventiltriebs, mit einer Schnittebene, die eine Längsachse der Schwenkwelle und eine Schwenkachse aufweist; und

Figur 5

beispielhafte Ventilhubsteuerkurven, die mit dem beispielhaften variablen Ventiltrieb erzeugbar sind.

The preferred embodiments and features of the invention described above can be combined with one another as desired. Further details and advantages of the invention are described below with reference to the accompanying drawings. Show it:

Figure 1

a sectional view of an exemplary variable valve train in a state in which a cam follower of the variable valve train is in contact with a base circle region of a cam of the camshaft;

Figure 2

another cross-sectional view of the exemplary variable valve train in a state in which the cam follower of the variable valve train is in contact with a valve lift region of the cam of the camshaft;

Figure 3

a perspective view of the exemplary variable valve train;

Figure 4

a further sectional view of the exemplary variable valve drive, with a sectional plane which has a longitudinal axis of the pivot shaft and a pivot axis; and

Figure 5

exemplary valve lift control curves that can be generated with the exemplary variable valve train.

The embodiments shown in the figures match at least in part, so that similar or identical parts are provided with the same reference numerals and reference is made to the description of the other embodiments or figures for their explanation in order to avoid repetition.

The Figures 1 to 4 show a variable valve train 10. Two gas exchange valves 12 (see in particular Figure 3 ), for example inlet valves or outlet valves, operated. The variable valve drive 10 can be included in an internal combustion engine of a motor vehicle, in particular a commercial vehicle. It is also possible for the variable valve drive to actuate only one gas exchange valve. There is also the possibility that the variable valve drive actuates several gas exchange valves via a valve bridge.

The variable valve drive 10 has a camshaft 14, a pivot lever element 16, two lever arms 18 and 20 and a rocker arm 22.

The camshaft 14 is rotatably mounted and has a cam 24. In some embodiments, the camshaft 14 can be connected to a camshaft adjuster 26 for adjusting a phase of the camshaft 14. The camshaft adjuster 26 is shown schematically in FIG Figure 2 indicated. In detail, the camshaft adjuster 26 can rotate the camshaft 14 by a predetermined angular amount clockwise or counterclockwise with respect to a drive by a crankshaft of the internal combustion engine. The opening and closing times of the gas exchange valves 12 can thus be shifted.

The pivot lever element 16 carries a cam follower 28. The cam follower 28 follows a cam contour of the cam 24 while the camshaft 14 rotates. The cam follower 28 is designed as a roller rotatably mounted about a cam follower axis 30. The cam follower shaft 30 is carried by a fork 32 of the pivot lever element 16 at opposite ends of the cam follower shaft 30. The fork 32 is arranged at a first end of the pivot lever element 16.

At one end of the pivot lever element 16 opposite the fork 32, the pivot lever element 16 is pivotably connected to the lever arms 18, 20. While the cam follower 28 follows the cam contour of the cam 24 during a rotation of the camshaft 14, the pivot lever element 16 is pivoted relative to the lever arms 18, 20. The pivot lever element 16 has a contact surface 34. The contact surface 34 serves as a contact surface for the rocker arm 22. The contact surface 34 extends concavely and is arranged on an upper side of the swivel lever element 16. The pivot lever element 16 thus serves as a backdrop for the rocker arm 22.

The lever arms 18, 20 are non-rotatably connected to a pivot shaft 36, so that they rotate together with the pivot shaft 36. In detail, the lever arms 18, 20 rotate when the pivot shaft 36 rotates about a longitudinal axis A of the pivot shaft 36. The pivot shaft 36 also serves as a rocker arm axis for the rocker arm 22. This is particularly advantageous for reasons of installation space, since there are no separate axes for pivoting the lever arms 18 , 20 and must be provided for pivoting the rocker arm 22.

The lever arms 18, 20 are connected to one another via the pivot shaft 36 and a pivot axis 38. The lever arms 18, 20 are arranged on opposite sides of the rocker arm 22. The lever arms 18, 20 encompass the pivot lever element 16 at the end of the pivot lever element 16 opposite the fork 32. The lever arms 18, 20 carry the pivot lever element 16 via the pivot axis 38, so that the pivot lever element 16 can be pivoted relative to the lever arms 18, 20. Here, the pivot lever element 16 can for example be connected to the pivot axis 38 in a rotationally fixed manner, the pivot axis 38 in turn being rotatably supported in the lever arms 18, 20. Alternatively, the pivot lever element 16 can be provided pivotably about the pivot axis 38. It is also possible that, for example, only one lever arm is provided which carries the pivot lever element.

In Figure 4 it is shown that the lever arms 18, 20 are connected to the pivot shaft 36 via a sleeve 40. In detail, the lever arms 18, 20 are non-rotatably connected to the sleeve 40, the sleeve 40 in turn being non-rotatably connected to the pivot shaft 36. The non-rotatable connections can be realized, for example, by a suitable fit, by welding, gluing, screwing, interlocking, etc.

In Figure 2 a drive unit 42, for example an electric drive, is shown schematically. The drive unit 42 is connected to the pivot shaft 36 so that the pivot shaft 36 can be rotated at least within a predetermined angular range, for example less than 360 °, in particular less than 90 °. The angular range depends on the lever arm lengths of the variable valve drive 10 and can, for example, as in the example shown, also be smaller than 20 °. A rotation of the pivot shaft 36 causes the lever arms 18 and 20 to pivot, since these are connected to the pivot shaft 36 in a rotationally fixed manner. Pivoting the lever arms 18 and 20 causes the pivoting lever element 16 to pivot. Here, the pivoting lever element 16 changes a position relative to the rocker arm 22 and the camshaft 14. This enables the cam contour of the cam 24 to be specifically transmitted via the pivoting lever element 16 to the rocker arm 22, which ultimately actuates the gas exchange valves 12 can be influenced, as will be described in more detail below.

As an alternative to the drive unit 42, an actuator 43 can also be provided. The actuator 43 can, for example, contact the first lever arm 18 and / or the second lever arm 20 in order to pivot the first and second lever arms 18, 20. A pivoting of the lever arms 18, 20 in turn causes a pivoting of the pivot lever element 16, as already mentioned above describe is. In such an embodiment, the lever arms 18, 20 can be rotatably connected to the pivot shaft 36, which thus only serves as a pivot axis.

In order to enable the pivot shaft (rocker arm axis) 36 to rotate, the pivot shaft 36 is rotatably mounted in bearing blocks 44, for example by means of slide bearings or roller bearings (see FIG Figure 3 ). The bearing blocks 44 can be fastened to a cylinder head of the internal combustion engine, for example by means of screws (not shown).

Referring again to FIG Figure 4 the rocker arm 22 is mounted pivotably about the sleeve 40 and thus pivotably about the pivot shaft 36. The provision of the sleeve 40 as an intermediate member between the pivot shaft 36 on the one hand and the lever arms 18, 20 and the rocker arm 22 on the other hand can simplify the assembly of the variable valve drive 10. In particular, an assembly consisting of the lever arms 18, 20, the rocker arm 22 and the sleeve 40 can be prefabricated, the lever arms 18, 20 being non-rotatably connected to the sleeve 40 and the rocker arm 22 being rotatably arranged around the sleeve 40. The sleeve 40 can then be connected non-rotatably to the pivot shaft 36. In other embodiments, the lever arms 18, 20 can be connected to the pivot shaft 36 in a rotationally fixed manner, for example, directly (that is to say without the interposition of a sleeve). As an alternative or in addition, the rocker arm 22 can be pivotably connected to the pivot shaft 36 directly (ie without the interposition of a sleeve). It is also possible to provide other configurations in which the lever arms 18, 20 are connected non-rotatably to the pivot shaft 36 and the rocker arm 22 is pivotably connected to the pivot shaft 36.

The rocker arm 22 has a fork 46 which carries a rotatable roller 48 via a roller axle 50. The rotatable roller 48 is in contact with the contact surface 34 of the pivot lever element 16. The cam follower 28 of the pivot lever element 16 and the rotatable roller 48 of the rocker arm 22 can be designed the same, since they transmit approximately the same forces and to reduce the variety of parts. The rocker arm 22 actuates the gas exchange valves 12, for example via a spherical foot (elephant foot, not shown).

In the Figures 1 and 2 shows how the variable valve train 10 produces an operative connection between the camshaft 14 and the gas exchange valves 12 during operation. In Figure 1 the cam follower 28 is in contact with a base circle portion of the cam 24. In Figure 2 the cam follower 28 is in contact with a valve lift area of the cam 24. In detail, the valve lift area of the cam contour of the cam 24 causes the Swivel lever element 16 about swivel axis 38, since cam follower 28 follows the cam contour of cam 24. The pivoting of the pivot lever element 16 about the pivot axis 38 causes the pivot lever 22 to pivot about the pivot shaft 36, since the roller 48 is in contact with the contact surface 34. In particular, when the pivoting lever element 16 is pivoted upward, the roller 48 rolls upwards on the contact surface 34 due to the rising ramp of the cam 24. The rocker arm 22 is pivoted about the pivot shaft 36. When the rocker arm 22 is pivoted, the gas exchange valves 12 are actuated (opened). When the pivot lever element 16 is pivoted downward due to the sloping ramp of the cam 24, the roller 48 rolls downward on the contact surface 34. The rocker arm 22 is pivoted back. The base circle area of the cam contour of the cam 24, on the other hand, does not cause any pivoting of the pivoting lever element 16 and thus also no pivoting of the rocker arm 22.

The Figure 5 shows exemplary valve lift curves for the gas exchange valves 12, which can be set with the variable valve train 10. Depending on the set angle of rotation of the pivot shaft 36 and the profile of the contact surface 34, different valve lifts (valve lift maxima) can be set. In particular, it can also be possible to generate a zero lift of the gas exchange valves 12. With reference to the Figures 1 and 2 an adjustment of the pivot shaft 36 in the clockwise direction causes the valve lift maxima of the gas exchange valves 12 to increase. By contrast, an adjustment of the pivot shaft 36 counterclockwise causes the valve lift maxima of the gas exchange valves 12 to decrease. This effect is achieved in that the relative position of the pivot axis 38 with respect to the camshaft 14 and the roller 48 is influenced by adjusting the pivot shaft 36. By shifting the pivot axis 38, the lever ratios between the camshaft 14 and the roller 48 are changed and thus the transmission ratio from the cam profile to the gas exchange valve 12. By shifting the pivot axis 38, another link profile section of the contact surface 34 comes into the cam tap (in contact with the roller 48). This can then ultimately influence the valve lift height.

The contact surface 34 of the pivot lever element 2 is to achieve the in Figure 5 specially designed valve lift curves. The, for example, concave course of the contact surface 34 must be designed so that the valve lift maxima of the valve lift curves can be influenced as desired by adjusting the lever arms 18. The contact surface 34 must, for example, depending on an arrangement and dimensioning of the camshaft 14, of the cam 24, the cam follower 28, the pivot lever element 16, the first lever arm 18, the second lever arm 20, the roller 48, the rocker arm 22, the pivot shaft 36, the pivot axis 38 and the gas exchange valves 12.

In combination with the camshaft adjuster 26, the valve lift curves can also be shifted (along the abscissa in Fig. 5 ) so that the opening and closing times can be varied.

List of reference symbols

10

Variable valve train

12

Gas exchange valve

14th

camshaft

16

Swivel lever element

18th

First lever arm

20th

Second lever arm

22nd

rocker arm

24

cam

26th

Camshaft adjuster

28

Cam follower

30th

Cam follower axis

32

fork

34

Contact surface

36

Swivel shaft

38

Swivel axis

40

Sleeve

42

Drive unit

43

Actuator

44

Bearing block

46

fork

48

role

50

Roller axis

A.

Longitudinal axis

Claims (15)

1. Variable valve train (10) for an internal combustion engine, comprising:

   a camshaft (14) with a cam (24);

   a rocker arm (22) for activating at least one gas exchange valve (12) of the internal combustion engine;

   a swivelling lever element (16), in particular a swivelling lever gate, which has a support surface (34) and a cam follower (28), wherein the support surface (34) is operatively connected, in particular in contact, with the rocker arm (22), and the cam follower (28) follows a cam contour of the cam (24); and characterized by

   a first lever arm (18), which pivotably mounts the swivelling lever element (16), and which is connected with a drivable swivelling shaft (36) for swivelling around a longitudinal axis (A) of the swivelling shaft (36) .
2. Variable valve train (10) according to Claim 1, wherein:

   the rocker arm (22) is mounted so that it can pivot around the swivelling shaft (36); and/or

   the swivelling shaft (36) serves as a rocker arm axis for the rocker arm (22).
3. Variable valve train (10) according to one of the preceding claims, wherein turning the swivelling shaft (36) causes the first lever arm (18) and the swivelling lever element (16) to pivot, making it possible to vary a transmission of the cam contour of the cam (24) from the swivelling lever element (16) to the rocker arm (22), in particular continuously.
4. Variable valve train (10) according to Claim 3, wherein the transmission for changing a maximum valve lift of the at least one gas exchange valve (12) is variable, in particular up to a zero lift of the at least one gas exchange valve (12).
5. Variable valve train (10) according to one of the preceding claims, wherein the first lever arm (18) is non-rotatably connected with the swivelling shaft (36).
6. Variable valve train (10) according to one of the preceding claims, wherein:

   the swivelling lever element (16) is swiveled relative to the first lever arm (18) while following the cam contour of the cam (24) via the cam follower (28); and/or

   a swivelling axis (38) pivotably joins the first lever arm (18) and swivelling lever element (16) together.
7. Variable valve train (10) according to one of the preceding claims, wherein the rocker arm (22) has a rotatable roller (48) for contacting the support surface (34) .
8. Variable valve train (10) according to Claim 7, wherein the cam follower (28) of the swivelling lever element (16) and the rotatable roller (48) of the rocker arm (22) have the same design.
9. Variable valve train (10) according to one of the preceding claims, wherein the swivelling shaft (36) can only be turned within a limited angular range of less than 360°, in particular within an angular range of less than 120°.
10. Variable valve train (10) according to one of the preceding claims, further comprising:
    a second lever arm (20), which is connected with the first lever arm (18) via the swivelling shaft (36), and in particular via the swivelling axis (38), wherein in particular the first lever arm (18) and second lever arm (20) are arranged on opposing sides of the rocker arm (22) .
11. Variable valve train (10) according to one of the preceding claims, further comprising:
    a sleeve (40), which is non-rotatably arranged on the swivelling shaft (36), wherein the first lever arm (18) is non-rotatably arranged on the sleeve (40), and the rocker arm (22) is arranged so that it can pivot around the sleeve (40).
12. Variable valve train (10) according to one of the preceding claims, wherein the swivelling lever element (16) is arranged between the rocker arm (22) and the camshaft (14).
13. Variable valve train (10) according to one of the preceding claims, further comprising:

    a drive unit (42) for turning the swivelling shaft (36); or

    an actuator (43), which is designed to contact the first lever arm (18) for swivelling the first lever arm (18) .
14. Variable valve train (10) according to one of the preceding claims, further comprising:
    a camshaft adjuster (26), which is connected with the camshaft (14) for adjusting a phase of the camshaft (14) .
15. Motor vehicle, in particular commercial vehicle, with a variable valve train (10) according to one of the preceding claims.

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